The GI diet started when Dr David Jenkins of the University of Toronto looked at the effects of different types of carbohydrates on diabetes patients, as our diet plan review explains. The initials in "GI diet" refer to the glycemic index, a scale of 1 - 100 that describes the speed at which we digest carbohydrates. Foods with a low glycemic index, such as porridge or beetroot, release glucose slowly and evenly. Foods with a high glycemic index provide a quick hit and encourage the body to release insulin, which then converts the excess glucose into fat.
The GI diet has been widely accepted by the medical industry as a healthy and effective way in which to lose weight. The diet meal plans involve eating food with a low score on the glycaemic index, generally considered to be foods that score 55 or less. There are many tables that chart the glycaemic index of food so it's a relatively easy diet to follow. The GI diet makes the calculations for you, following the conventions of traffic light colours. Red light foods (which score high on the index) should be avoided if you want to lose weight. Yellow light foods (which have a medium score ie 50 - 70) can be used occasionally whilst you can eat as much as you like of green light foods (low on the glycaemic index).
There are many more health benefits to eating foods with a low glycaemic index than just weight loss. Followers of the programme claim increased energy levels, as well as reduced risk of a heart attack or stroke. There are no serious critics of the programme as everyone agrees with its commonsense methodology.